A/HRC/12/37 page 11 that either there was no large-scale abuse of civilians and civilian objects by combatants, or that civilians’ deaths could not be explained as resulting from the presence of fighters in civilian areas.40 25. Any civilian object becomes a legitimate military objective only if, by its nature, location, purpose or use, it makes an effective contribution to military action, and if its total or partial destruction in the circumstances ruling at the time offers a definite military advantage. Yet, even if an object loses its essentially civilian character, the attacker must still refrain from any attack that may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated. Moreover, article 53 of the Fourth Geneva Convention prohibits, unless absolutely necessary by military operations, “[a]ny destruction by the Occupying Power of real or personal property belonging individually or collectively to private persons, or to the State, or to other public authorities, or to social or cooperative organizations”. 26. Israel asserts that it took measures to warn the civilian population of Gaza of imminent attacks, including through the dropping of leaflets, recorded telephone calls and text messages to mobile phones during the conflict. The accuracy and general effectiveness of these warnings have been called into question.41 In any event, the use of such warnings does not discharge Israel of the duty to consider the proportionality of any attack on a target which may include civilians. Alleged use of white phosphorous 27. IDF used white phosphorous, a substance with a highly incendiary effect, in densely populated, built-up areas of Gaza City.42 The use of munitions containing phosphorous is not, as such, prohibited under international law, in particular for marking and smokescreen purposes. However, the use of white phosphorus in airburst method over densely populated areas is inevitably indiscriminate, insofar as its wide dispersal means that it is impossible to direct it towards only military targets. B. Reported failure to protect medical personnel and to evacuate the wounded 28. There are reports of failures on the part of the Israeli military to meet its obligation under international humanitarian law to protect medical personnel and to care for and evacuate the 40 Amnesty International, Operation “Cast Lead”, pp. 4 and 75; Human Rights Watch, Rain of Fire: Israel’s Unlawful Use of White Phosphorus in Gaza, 25 March 2009, p. 5. 41 Amnesty International, Operation “Cast Lead”, op. cit., pp. 50-51 and B’Tselem, “Guidelines for Israel’s Investigation into Operation Cast Lead”, pp. 10-11. 42 See Amnesty International, Israel/OPT: Fuelling conflict, p. 11; Human Rights Watch, Rain of Fire, pp. 1-2, 31 and 58. A delegation from Amnesty International reported finding white phosphorous still burning in residential areas in several parts of Gaza days after the hostilities stopped on 18 January. See also No Safe Place, paras. 478 and 487-489.